/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.logging.impl;

import java.io.InputStream;
import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogConfigurationException;

/**
 * <p>
 * Simple implementation of Log that sends all enabled log messages, for all
 * defined loggers, to System.err. The following system properties are supported
 * to configure the behavior of this logger:
 * </p>
 * <ul>
 * <li><code>org.apache.commons.logging.simplelog.defaultlog</code> - Default
 * logging detail level for all instances of SimpleLog. Must be one of ("trace",
 * "debug", "info", "warn", "error", or "fatal"). If not specified, defaults to
 * "info".</li>
 * <li><code>org.apache.commons.logging.simplelog.log.xxxxx</code> - Logging
 * detail level for a SimpleLog instance named "xxxxx". Must be one of ("trace",
 * "debug", "info", "warn", "error", or "fatal"). If not specified, the default
 * logging detail level is used.</li>
 * <li><code>org.apache.commons.logging.simplelog.showlogname</code> - Set to
 * <code>true</code> if you want the Log instance name to be included in output
 * messages. Defaults to <code>false</code>.</li>
 * <li><code>org.apache.commons.logging.simplelog.showShortLogname</code> - Set
 * to <code>true</code> if you want the last component of the name to be
 * included in output messages. Defaults to <code>true</code>.</li>
 * <li><code>org.apache.commons.logging.simplelog.showdatetime</code> - Set to
 * <code>true</code> if you want the current date and time to be included in
 * output messages. Default is <code>false</code>.</li>
 * <li><code>org.apache.commons.logging.simplelog.dateTimeFormat</code> - The
 * date and time format to be used in the output messages. The pattern
 * describing the date and time format is the same that is used in
 * <code>java.text.SimpleDateFormat</code>. If the format is not specified or is
 * invalid, the default format is used. The default format is
 * <code>yyyy/MM/dd HH:mm:ss:SSS zzz</code>.</li>
 * </ul>
 * 
 * <p>
 * In addition to looking for system properties with the names specified above,
 * this implementation also checks for a class loader resource named
 * <code>"simplelog.properties"</code>, and includes any matching definitions
 * from this resource (if it exists).
 * </p>
 * 
 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a>
 * @author Rod Waldhoff
 * @author Robert Burrell Donkin
 * 
 * @version $Id: SimpleLog.java,v 1.21 2004/06/06 20:47:56 rdonkin Exp $
 */
public class SimpleLog implements Log, Serializable {

  private static final long serialVersionUID = 136942970684951178L;

  // ------------------------------------------------------- Class Attributes

  /** All system properties used by <code>SimpleLog</code> start with this */
  static protected final String systemPrefix = "org.apache.commons.logging.simplelog.";

  /** Properties loaded from simplelog.properties */
  static protected final Properties simpleLogProps = new Properties();

  /** The default format to use when formating dates */
  static protected final String DEFAULT_DATE_TIME_FORMAT = "yyyy/MM/dd HH:mm:ss:SSS zzz";

  /** Include the instance name in the log message? */
  static protected boolean showLogName = false;
  /**
   * Include the short name ( last component ) of the logger in the log message.
   * Defaults to true - otherwise we'll be lost in a flood of messages without
   * knowing who sends them.
   */
  static protected boolean showShortName = true;
  /** Include the current time in the log message */
  static protected boolean showDateTime = false;
  /** The date and time format to use in the log message */
  static protected String dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
  /** Used to format times */
  static protected DateFormat dateFormatter = null;

  // ---------------------------------------------------- Log Level Constants

  /** "Trace" level logging. */
  public static final int LOG_LEVEL_TRACE = 1;
  /** "Debug" level logging. */
  public static final int LOG_LEVEL_DEBUG = 2;
  /** "Info" level logging. */
  public static final int LOG_LEVEL_INFO = 3;
  /** "Warn" level logging. */
  public static final int LOG_LEVEL_WARN = 4;
  /** "Error" level logging. */
  public static final int LOG_LEVEL_ERROR = 5;
  /** "Fatal" level logging. */
  public static final int LOG_LEVEL_FATAL = 6;

  /** Enable all logging levels */
  public static final int LOG_LEVEL_ALL = (LOG_LEVEL_TRACE - 1);

  /** Enable no logging levels */
  public static final int LOG_LEVEL_OFF = (LOG_LEVEL_FATAL + 1);

  // ------------------------------------------------------------ Initializer

  private static String getStringProperty(String name) {
    String prop = null;
    try {
      prop = System.getProperty(name);
    } catch (SecurityException e) {
      ; // Ignore
    }
    return (prop == null) ? simpleLogProps.getProperty(name) : prop;
  }

  private static String getStringProperty(String name, String dephault) {
    String prop = getStringProperty(name);
    return (prop == null) ? dephault : prop;
  }

  private static boolean getBooleanProperty(String name, boolean dephault) {
    String prop = getStringProperty(name);
    return (prop == null) ? dephault : "true".equalsIgnoreCase(prop);
  }

  // Initialize class attributes.
  // Load properties file, if found.
  // Override with system properties.
  static {
    // Add props from the resource simplelog.properties
    InputStream in = getResourceAsStream("simplelog.properties");
    if (null != in) {
      try {
        simpleLogProps.load(in);
        in.close();
      } catch (java.io.IOException e) {
        // ignored
      }
    }

    showLogName = getBooleanProperty(systemPrefix + "showlogname", showLogName);
    showShortName = getBooleanProperty(systemPrefix + "showShortLogname",
        showShortName);
    showDateTime = getBooleanProperty(systemPrefix + "showdatetime",
        showDateTime);

    if (showDateTime) {
      dateTimeFormat = getStringProperty(systemPrefix + "dateTimeFormat",
          dateTimeFormat);
      try {
        dateFormatter = new SimpleDateFormat(dateTimeFormat);
      } catch (IllegalArgumentException e) {
        // If the format pattern is invalid - use the default format
        dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
        dateFormatter = new SimpleDateFormat(dateTimeFormat);
      }
    }
  }

  // ------------------------------------------------------------- Attributes

  /** The name of this simple log instance */
  protected String logName = null;
  /** The current log level */
  protected int currentLogLevel;
  /** The short name of this simple log instance */
  private String shortLogName = null;

  // ------------------------------------------------------------ Constructor

  /**
   * Construct a simple log with given name.
   * 
   * @param name
   *          log name
   */
  public SimpleLog(String name) {

    logName = name;

    // Set initial log level
    // Used to be: set default log level to ERROR
    // IMHO it should be lower, but at least info ( costin ).
    setLevel(SimpleLog.LOG_LEVEL_INFO);

    // Set log level from properties
    String lvl = getStringProperty(systemPrefix + "log." + logName);
    int i = String.valueOf(name).lastIndexOf(".");
    while (null == lvl && i > -1) {
      name = name.substring(0, i);
      lvl = getStringProperty(systemPrefix + "log." + name);
      i = String.valueOf(name).lastIndexOf(".");
    }

    if (null == lvl) {
      lvl = getStringProperty(systemPrefix + "defaultlog");
    }

    if ("all".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_ALL);
    } else if ("trace".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_TRACE);
    } else if ("debug".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_DEBUG);
    } else if ("info".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_INFO);
    } else if ("warn".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_WARN);
    } else if ("error".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_ERROR);
    } else if ("fatal".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_FATAL);
    } else if ("off".equalsIgnoreCase(lvl)) {
      setLevel(SimpleLog.LOG_LEVEL_OFF);
    }

  }

  // -------------------------------------------------------- Properties

  /**
   * <p>
   * Set logging level.
   * </p>
   * 
   * @param currentLogLevel
   *          new logging level
   */
  public void setLevel(int currentLogLevel) {

    this.currentLogLevel = currentLogLevel;

  }

  /**
   * <p>
   * Get logging level.
   * </p>
   */
  public int getLevel() {

    return currentLogLevel;
  }

  // -------------------------------------------------------- Logging Methods

  /**
   * <p>
   * Do the actual logging. This method assembles the message and then calls
   * <code>write()</code> to cause it to be written.
   * </p>
   * 
   * @param type
   *          One of the LOG_LEVEL_XXX constants defining the log level
   * @param message
   *          The message itself (typically a String)
   * @param t
   *          The exception whose stack trace should be logged
   */
  protected void log(int type, Object message, Throwable t) {
    // Use a string buffer for better performance
    StringBuffer buf = new StringBuffer();

    // Append date-time if so configured
    if (showDateTime) {
      buf.append(dateFormatter.format(new Date()));
      buf.append(" ");
    }

    // Append a readable representation of the log level
    switch (type) {
    case SimpleLog.LOG_LEVEL_TRACE:
      buf.append("[TRACE] ");
      break;
    case SimpleLog.LOG_LEVEL_DEBUG:
      buf.append("[DEBUG] ");
      break;
    case SimpleLog.LOG_LEVEL_INFO:
      buf.append("[INFO] ");
      break;
    case SimpleLog.LOG_LEVEL_WARN:
      buf.append("[WARN] ");
      break;
    case SimpleLog.LOG_LEVEL_ERROR:
      buf.append("[ERROR] ");
      break;
    case SimpleLog.LOG_LEVEL_FATAL:
      buf.append("[FATAL] ");
      break;
    }

    // Append the name of the log instance if so configured
    if (showShortName) {
      if (shortLogName == null) {
        // Cut all but the last component of the name for both styles
        shortLogName = logName.substring(logName.lastIndexOf(".") + 1);
        shortLogName = shortLogName
            .substring(shortLogName.lastIndexOf("/") + 1);
      }
      buf.append(String.valueOf(shortLogName)).append(" - ");
    } else if (showLogName) {
      buf.append(String.valueOf(logName)).append(" - ");
    }

    // Append the message
    buf.append(String.valueOf(message));

    // Append stack trace if not null
    if (t != null) {
      buf.append(" <");
      buf.append(t.toString());
      buf.append(">");

      java.io.StringWriter sw = new java.io.StringWriter(1024);
      java.io.PrintWriter pw = new java.io.PrintWriter(sw);
      t.printStackTrace(pw);
      pw.close();
      buf.append(sw.toString());
    }

    // Print to the appropriate destination
    write(buf);

  }

  /**
   * <p>
   * Write the content of the message accumulated in the specified
   * <code>StringBuffer</code> to the appropriate output destination. The
   * default implementation writes to <code>System.err</code>.
   * </p>
   * 
   * @param buffer
   *          A <code>StringBuffer</code> containing the accumulated text to be
   *          logged
   */
  protected void write(StringBuffer buffer) {

    System.err.println(buffer.toString());

  }

  /**
   * Is the given log level currently enabled?
   * 
   * @param logLevel
   *          is this level enabled?
   */
  protected boolean isLevelEnabled(int logLevel) {
    // log level are numerically ordered so can use simple numeric
    // comparison
    return (logLevel >= currentLogLevel);
  }

  // -------------------------------------------------------- Log Implementation

  /**
   * <p>
   * Log a message with debug log level.
   * </p>
   */
  public final void debug(Object message) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_DEBUG)) {
      log(SimpleLog.LOG_LEVEL_DEBUG, message, null);
    }
  }

  /**
   * <p>
   * Log an error with debug log level.
   * </p>
   */
  public final void debug(Object message, Throwable t) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_DEBUG)) {
      log(SimpleLog.LOG_LEVEL_DEBUG, message, t);
    }
  }

  /**
   * <p>
   * Log a message with trace log level.
   * </p>
   */
  public final void trace(Object message) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_TRACE)) {
      log(SimpleLog.LOG_LEVEL_TRACE, message, null);
    }
  }

  /**
   * <p>
   * Log an error with trace log level.
   * </p>
   */
  public final void trace(Object message, Throwable t) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_TRACE)) {
      log(SimpleLog.LOG_LEVEL_TRACE, message, t);
    }
  }

  /**
   * <p>
   * Log a message with info log level.
   * </p>
   */
  public final void info(Object message) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_INFO)) {
      log(SimpleLog.LOG_LEVEL_INFO, message, null);
    }
  }

  /**
   * <p>
   * Log an error with info log level.
   * </p>
   */
  public final void info(Object message, Throwable t) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_INFO)) {
      log(SimpleLog.LOG_LEVEL_INFO, message, t);
    }
  }

  /**
   * <p>
   * Log a message with warn log level.
   * </p>
   */
  public final void warn(Object message) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_WARN)) {
      log(SimpleLog.LOG_LEVEL_WARN, message, null);
    }
  }

  /**
   * <p>
   * Log an error with warn log level.
   * </p>
   */
  public final void warn(Object message, Throwable t) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_WARN)) {
      log(SimpleLog.LOG_LEVEL_WARN, message, t);
    }
  }

  /**
   * <p>
   * Log a message with error log level.
   * </p>
   */
  public final void error(Object message) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_ERROR)) {
      log(SimpleLog.LOG_LEVEL_ERROR, message, null);
    }
  }

  /**
   * <p>
   * Log an error with error log level.
   * </p>
   */
  public final void error(Object message, Throwable t) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_ERROR)) {
      log(SimpleLog.LOG_LEVEL_ERROR, message, t);
    }
  }

  /**
   * <p>
   * Log a message with fatal log level.
   * </p>
   */
  public final void fatal(Object message) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_FATAL)) {
      log(SimpleLog.LOG_LEVEL_FATAL, message, null);
    }
  }

  /**
   * <p>
   * Log an error with fatal log level.
   * </p>
   */
  public final void fatal(Object message, Throwable t) {

    if (isLevelEnabled(SimpleLog.LOG_LEVEL_FATAL)) {
      log(SimpleLog.LOG_LEVEL_FATAL, message, t);
    }
  }

  /**
   * <p>
   * Are debug messages currently enabled?
   * </p>
   * 
   * <p>
   * This allows expensive operations such as <code>String</code> concatenation
   * to be avoided when the message will be ignored by the logger.
   * </p>
   */
  public final boolean isDebugEnabled() {

    return isLevelEnabled(SimpleLog.LOG_LEVEL_DEBUG);
  }

  /**
   * <p>
   * Are error messages currently enabled?
   * </p>
   * 
   * <p>
   * This allows expensive operations such as <code>String</code> concatenation
   * to be avoided when the message will be ignored by the logger.
   * </p>
   */
  public final boolean isErrorEnabled() {

    return isLevelEnabled(SimpleLog.LOG_LEVEL_ERROR);
  }

  /**
   * <p>
   * Are fatal messages currently enabled?
   * </p>
   * 
   * <p>
   * This allows expensive operations such as <code>String</code> concatenation
   * to be avoided when the message will be ignored by the logger.
   * </p>
   */
  public final boolean isFatalEnabled() {

    return isLevelEnabled(SimpleLog.LOG_LEVEL_FATAL);
  }

  /**
   * <p>
   * Are info messages currently enabled?
   * </p>
   * 
   * <p>
   * This allows expensive operations such as <code>String</code> concatenation
   * to be avoided when the message will be ignored by the logger.
   * </p>
   */
  public final boolean isInfoEnabled() {

    return isLevelEnabled(SimpleLog.LOG_LEVEL_INFO);
  }

  /**
   * <p>
   * Are trace messages currently enabled?
   * </p>
   * 
   * <p>
   * This allows expensive operations such as <code>String</code> concatenation
   * to be avoided when the message will be ignored by the logger.
   * </p>
   */
  public final boolean isTraceEnabled() {

    return isLevelEnabled(SimpleLog.LOG_LEVEL_TRACE);
  }

  /**
   * <p>
   * Are warn messages currently enabled?
   * </p>
   * 
   * <p>
   * This allows expensive operations such as <code>String</code> concatenation
   * to be avoided when the message will be ignored by the logger.
   * </p>
   */
  public final boolean isWarnEnabled() {

    return isLevelEnabled(SimpleLog.LOG_LEVEL_WARN);
  }

  /**
   * Return the thread context class loader if available. Otherwise return null.
   * 
   * The thread context class loader is available for JDK 1.2 or later, if
   * certain security conditions are met.
   * 
   * @exception LogConfigurationException
   *              if a suitable class loader cannot be identified.
   */
  private static ClassLoader getContextClassLoader() {
    ClassLoader classLoader = null;

    if (classLoader == null) {
      try {
        // Are we running on a JDK 1.2 or later system?
        Method method = Thread.class.getMethod("getContextClassLoader", null);

        // Get the thread context class loader (if there is one)
        try {
          classLoader = (ClassLoader) method.invoke(Thread.currentThread(),
              null);
        } catch (IllegalAccessException e) {
          ; // ignore
        } catch (InvocationTargetException e) {
          /**
           * InvocationTargetException is thrown by 'invoke' when the method
           * being invoked (getContextClassLoader) throws an exception.
           * 
           * getContextClassLoader() throws SecurityException when the context
           * class loader isn't an ancestor of the calling class's class loader,
           * or if security permissions are restricted.
           * 
           * In the first case (not related), we want to ignore and keep going.
           * We cannot help but also ignore the second with the logic below, but
           * other calls elsewhere (to obtain a class loader) will trigger this
           * exception where we can make a distinction.
           */
          if (e.getTargetException() instanceof SecurityException) {
            ; // ignore
          } else {
            // Capture 'e.getTargetException()' exception for details
            // alternate: log 'e.getTargetException()', and pass back 'e'.
            throw new LogConfigurationException(
                "Unexpected InvocationTargetException", e.getTargetException());
          }
        }
      } catch (NoSuchMethodException e) {
        // Assume we are running on JDK 1.1
        ; // ignore
      }
    }

    if (classLoader == null) {
      classLoader = SimpleLog.class.getClassLoader();
    }

    // Return the selected class loader
    return classLoader;
  }

  private static InputStream getResourceAsStream(final String name) {
    return (InputStream) AccessController.doPrivileged(new PrivilegedAction() {
      public Object run() {
        ClassLoader threadCL = getContextClassLoader();

        if (threadCL != null) {
          return threadCL.getResourceAsStream(name);
        } else {
          return ClassLoader.getSystemResourceAsStream(name);
        }
      }
    });
  }
}
